Asphalt roofing shingles commonly used on commercial or residential structures are generally made in a known method which includes an asphalt coated substrate. During the manufacturing process, a substrate sheet or web is coated with hot asphalt before being processed through a series of rollers or drums that press and evenly apply the hot asphalt onto the substrate sheet. The substrate sheet or web may be any one known in the art or hereafter developed for asphalt roofing shingles, including a fiberglass mat, a polyester mat, or an organic paper mat, such as those made from materials such as recycled cardboard or paper, or a woven or non-woven mat made from a fibrous material such as cellulose fibers, synthetic fibers, mineral fibers and the like, or any mixture thereof. The substrate sheet is also typically coated with one or more layers of weathering materials to protect the roofing shingles from natural elements such as ultraviolet rays, rain, snow and the like and is then cooled. After cooling, the sheet is cut into a plurality of individual shingles of desired size and the individual shingles are then stacked in bundles for shipment.
Because the asphalt applied to the substrate sheet is both hot and sticky, it has a tendency to stick to the rollers and/or drums associated with the manufacturing equipment that coat and press the asphalt onto the substrate. As a result, prior to making contact with certain rollers and/or drums, an aggregate layer is normally applied to prevent the hot, sticky asphalt from sticking to or gumming up the rollers during the manufacturing process. Presently, roofing shingle manufacturers add colored granules to the front surface to protect the weathering side of the shingle and cheaper, non-sticking silicon particulates, such as sand or talc, to one side of the hot asphalt layer to prevent the substrate from sticking to the rollers. Using a granular aggregate backing particulate material like sand, talc, mica, coal slag fines, or volcanic ash has a significant downside as explained below.
Sand and other backing particulates are expensive, especially when purchased and used in high volume, as in the roofing shingle manufacturing process. Sand and other particulates are generally abrasive and penetrate the moving parts of the manufacturing equipment. The abrasive edges of the backing particulates cause serious wear and tear to the rollers, drums, gears and other mechanisms associated with the equipment. Repairing and replacing manufacturing equipment is expensive. Using sand and these other aggregate backing particulates also creates waste as more backing material is applied than necessary to ensure complete coverage of the surface. In addition, sand and other aggregate backing particulates potentially expose employees engaged in the manufacturing process to silica that may subject the employees to harmful health effects.
It is therefore desirable to develop a liquid release agent and methods for applying the same for use in the process of manufacturing roofing shingles wherein the liquid release agent and associated methods effectively prevent hot asphalt from sticking to rollers, drums and other surfaces used in the manufacturing process and likewise prevent the individual shingles from sticking to one another when stacked, stored, and/or shipped. Removing silica or sand from the manufacturing process will likewise improve employee working conditions and employee health and safety by making it easier to reduce or eliminate employee exposure to silica fines and dust. Further, removing silica, sand and the other backing particulates from the manufacturing process is likely to increase equipment reliability, sustainability, reduce maintenance costs and may reduce raw material volume and cost.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.